For the gas-phase equilibrium 2 ,NO_2(g) N_2O_4(g) (K_p = 0.67 ) at 298 K

CHEMISTRY · Single correct · A Level · Chemistry · Chemical equilibria (Le Chatelier’s principle and Kc) · Chemical equilibria (Le Chatelier’s principle and Kc)

Problem

For the gas-phase equilibrium 2 NO2(g)⇌N2O4(g)\mathrm{2\,NO_2(g) \rightleftharpoons N_2O_4(g)} Kp=0.67K_p = 0.67 at 298 K. A rigid container at this temperature initially contains an equilibrium mixture with partial pressures PNO2=0.40 atmP_{\mathrm{NO_2}} = 0.40\,\text{atm} and PN2O4=0.13 atm.P_{\mathrm{N_2O_4}} = 0.13\,\text{atm}. The container’s volume is then suddenly doubled at constant temperature. Which of the following gives the value of the reaction quotient QpQ_p immediately after the volume change, and predicts the net direction of the reaction as equilibrium is re-established? (a) Qp≈0.33; the reaction will shift right to form more N2O4Q_p \approx 0.33;\ \text{the reaction will shift right to form more }\mathrm{N_2O_4} (b) Qp≈0.81; the reaction will remain at equilibrium with no net shiftQ_p \approx 0.81;\ \text{the reaction will remain at equilibrium with no net shift} (c) Qp≈1.6; the reaction will shift left to form more NO2Q_p \approx 1.6;\ \text{the reaction will shift left to form more }\mathrm{NO_2} (d) Qp≈1.6; the reaction will shift right to form more N2O4Q_p \approx 1.6;\ \text{the reaction will shift right to form more }\mathrm{N_2O_4}

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